ladybird/Libraries/LibWeb/HTML/HTMLHeadingElement.cpp

/*
 * Copyright (c) 2018-2020, Andreas Kling <andreas@ladybird.org>
 * Copyright (c) 2025, Sam Atkins <sam@ladybird.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <LibWeb/Bindings/HTMLHeadingElement.h>
#include <LibWeb/Bindings/Intrinsics.h>
#include <LibWeb/CSS/ComputedProperties.h>
#include <LibWeb/CSS/StyleValues/KeywordStyleValue.h>
#include <LibWeb/DOM/Document.h>
#include <LibWeb/HTML/HTMLHeadingElement.h>

namespace Web::HTML {

GC_DEFINE_ALLOCATOR(HTMLHeadingElement);

HTMLHeadingElement::HTMLHeadingElement(DOM::Document& document, DOM::QualifiedName qualified_name)
    : HTMLElement(document, move(qualified_name))
{
}

HTMLHeadingElement::~HTMLHeadingElement() = default;

void HTMLHeadingElement::initialize(JS::Realm& realm)
{
    WEB_SET_PROTOTYPE_FOR_INTERFACE(HTMLHeadingElement);
    Base::initialize(realm);
}

bool HTMLHeadingElement::is_presentational_hint(FlyString const& name) const
{
    if (Base::is_presentational_hint(name))
        return true;

    return name == HTML::AttributeNames::align;
}

// https://html.spec.whatwg.org/multipage/rendering.html#tables-2
void HTMLHeadingElement::apply_presentational_hints(Vector<CSS::StyleProperty>& properties) const
{
    HTMLElement::apply_presentational_hints(properties);
    for_each_attribute([&](auto& name, auto& value) {
        if (name == HTML::AttributeNames::align) {
            if (value == "left"sv)
                properties.append({ .property_id = CSS::PropertyID::TextAlign, .value = CSS::KeywordStyleValue::create(CSS::Keyword::Left) });
            else if (value == "right"sv)
                properties.append({ .property_id = CSS::PropertyID::TextAlign, .value = CSS::KeywordStyleValue::create(CSS::Keyword::Right) });
            else if (value == "center"sv)
                properties.append({ .property_id = CSS::PropertyID::TextAlign, .value = CSS::KeywordStyleValue::create(CSS::Keyword::Center) });
            else if (value == "justify"sv)
                properties.append({ .property_id = CSS::PropertyID::TextAlign, .value = CSS::KeywordStyleValue::create(CSS::Keyword::Justify) });
        }
    });
}

// https://html.spec.whatwg.org/multipage/sections.html#heading-level
WebIDL::UnsignedLong HTMLHeadingElement::heading_level() const
{
    // h1–h6 elements have a heading level, which is given by getting the element's computed heading level.
    if (m_dom_tree_version_for_cached_heading_level < document().dom_tree_version()) {
        m_dom_tree_version_for_cached_heading_level = document().dom_tree_version();
        m_cached_heading_level = computed_heading_level();
    }
    return m_cached_heading_level;
}

}